Dye compound and photoelectric component using the same

ABSTRACT

The present invention relates to a dye compound represented by the following formula (I), or a salt thereof: 
     
       
         
         
             
             
         
       
     
     wherein R 1 , R 2 , R 3 , R 4 , D 1 , D 2 , B, and n are defined the same as the specification, and also relates to a photoelectric component using the same. The dye compound of the present invention is suitable for Dye-Sensitized Solar Cell (DSSC). Hence, the photoelectric characteristics of the DSSC can be improved by using the dye compound of the present invention.

This application is a divisional application of U.S. patent applicationSer. No. 12/320,232, filed Jan. 22, 2009, which has issued as U.S. Pat.No. 8,203,068 (of which the entire disclosure of the pending, priorapplication is hereby incorporated by reference).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a dye compound and a photoelectriccomponent using the same and, more particularly, to a dye compound,which is used for the dye-sensitized solar cell (DSSC), and aphotoelectric component using the same.

2. Description of Related Art

With the development of industrial technology, the serious problems thatthe whole world is facing today are the energy crisis and theenvironmental pollution. In order to solve the global energy crisis andto reduce the environmental pollution, one of the effective means is thesolar cell, which can convert the solar energy into the electricity.Since the dye-sensitized solar cell has the advantages of lowmanufacturing cost, large-scale production, great flexibility, lighttransmittance, and being capable of use in the buildings, theapplication of the dye-sensitized solar cell becomes more and moreattractive.

Currently, Grätzel et al. have disclosed a series of literatures, forexample, O'Regan, B.; Grätzel, M. Nature 1991, 353, 737, which shows thepracticability of the dye-sensitized solar cell. The general structureof the dye-sensitized solar cell comprises an anode, a cathode, anano-porous titanium dioxide layer, a dye, and electrolyte, wherein thedye plays a critical role in the conversion efficiency of thedye-sensitized solar cell. The dye suitable for the dye-sensitized solarcell must have characteristics in broad absorption spectrum, high molarabsorption coefficient, thermal stability, and light stability.

The ruthenium complexes are the sensitized dyes with the higherconversion efficiency nowadays. However, the manufacturing cost of theruthenium complexes is high, and there may be problems of short supplywhen the ruthenium complexes are used widely. The organic sensitizersfor the dye-sensitized solar cell have advantages of high molarabsorption coefficient. Besides, it is possible to produce variousorganic sensitizers through molecular design. Hence, dye-sensitizedsolar cells with different colors can be manufactured to improve theapplication flexibility of the dye-sensitized solar cells. In addition,it is also possible to change the color of the dye-sensitized solar cellto match with the color of objects. Currently, dye derivatives, such ascoumarin (Hara, K.; Sayama, K.; Arakawa, H.; Ohga, Y.; Shinpo, A.; Sug,S. Chem. Commun. 2001, 569), indoline (Horiuchi, T.; Miura, H.; Sumioka,K.; Uchida, S. J. Am. Chem. Soc. 2004, 126, 12218), and merocyanine(Otaka, H.; Kira, M.; Yano, K.; Ito, S.; Mitekura, H.; Kawata, T.;Matsui, F. J Photochem. Photobiol. A: Chem. 2004, 164, 67), have alreadyapplied in the manufacture of dye-sensitized solar cells.

However, the process for synthesis of sensitized dyes is verycomplicated, and it is difficult to control the synthesis condition ofsensitized dyes.

The dyes for the dye-sensitized solar cell influence the conversionefficiency critically. Hence, it is desirable to provide a dye compound,which can improve the conversion efficiency of the dye-sensitized solarcell. In addition, it is also important to simplify the method forsynthesis of dye compounds, in order to reduce the cost of manufacturingdye-sensitized solar cells.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a novel dye compound,which is suitable for a dye-sensitized solar cell. In addition, the dyecompound of the present invention has high molar absorption coefficient,so that it is possible to improve the photoelectric conversionefficiency of a dye-sensitized solar cell by the dye compound of thepresent invention.

Another object of the present invention is to provide a simple methodfor synthesis of a dye compound, wherein the synthesis steps of the dyecompound is less, the process is easy to control, and the cost ofsynthesis is lower.

Furthermore, another object of the present invention is to provide adye-sensitized solar cell, which shows higher photoelectric conversionefficiency.

Hence, the present invention provides a dye compound represented by thefollowing formula (I), or a salt thereof:

wherein,R₁, R₂, R₃, and R₄ are each independently H, C₁˜C₁₂ alkyl, C₁˜C₁₂alkoxy, or a halogen, and n is 1, 2, or 3;D₁, and D₂ are each independently C₁˜C₁₂ alkyl,

or D₁, D₂,and N bond together to form

(i.e. C₄˜C₆ cycloheteroalkylene), wherein R₅, R₆, R₇, R₈, R₁₀, R₁₁, R₁₃,and R₁₄ are each independently H, C₁˜C₁₂ alkyl, C₁˜C₁₂ alkoxy, amino, orhalogen, and R₉, R₁₂, and R₁₅ are each independently H, or C₁˜C₁₂ alkyl;B is

wherein R₁₆, R₁₇, and R₁₈ are each independently H, C₁˜C₁₂ alkyl, C₁˜C₁₂alkoxy, or halogen, R₁₉, R₂₀, R₂₁, and R₂₂ are each independently H, orC₁˜C₁₂ alkyl, and Z is O, S, or Se.

In the above formula (I), R₁, R₂, R₃, and R₄ are each independently H,C₁˜C₁₂ alkyl, C₁˜C₁₂ alkoxy, or halogen, and n is 1, 2, or 3.Preferably, R₁, R₂, R₃, and R₄ are each independently H, C₁˜C₁₂ alkyl,C₁˜C₁₂ alkoxy, or halogen, and n is 1, or 2. More preferably, R₁, R₂,R₃, and R₄ are each independently H, C₁˜C₁₂ alkyl, or C₁˜C₁₂ alkoxy, andn is 1, or 2. Still more preferably, R₁, R₂, R₃, and R₄ are eachindependently H, C₁˜C₁₂ alkyl, or C₁˜C₁₂ alkoxy, and n is 1. Mortpreferably, R₁, R₂, R₃, and R₄ are each independently H, or C₁˜C₁₂alkyl, and n is 1.

In the above formula (I), D₁, and D₂ are each independently C₁˜C₁₂alkyl,

or D₁, D₂, and N bond together to form

(i.e. C₄˜C₆ cycloheteroalkylene), wherein R₅, R₆, R₇, R₈, R₁₀, R₁₁, R₁₃,and R₁₄ are each independently H, C₁˜C₁₂ alkyl, C₁˜C₁₂ alkoxy, amino, orhalogen, and R₉, R₁₂, and R₁₅ are each independently H, or C₁˜C₁₂ alkyl.Preferably, D₁, and D₂ are each independently C₁˜C₁₂ alkyl,

wherein R₅, R₆, R₇, and R₈ are each independently H, C₁˜C₁₂ alkyl,C₁˜C₁₂ alkoxy, amino, or halogen, and R₉, is H, or C₁˜C₁₂ alkyl. Morepreferably, D₁, and D₂ are each independently C₁˜C₁₂ alkyl,

wherein R₅, R₆, R₇, and R₈ are each independently H, C₁˜C₁₂ alkyl, orC₁˜C₁₂ alkoxy, and R₉, is H, or C₁˜C₁₂ alkyl. Most preferably, D₁, andD₂ are each independently C₁˜C₁₂ alkyl,

wherein R₅, R₆, R₇, R₈, and R₉ are each independently H, or C₁˜C₁₂alkyl.

In addition, according to one embodiment of the present invention, inthe above formula (I), D₁, and D₂ are each independently C₁˜C₁₂ alkyl,or

wherein R₅, R₆, and R₇ are each independently H, C₁˜C₁₂ alkyl, C₁˜C₁₂alkoxy, amino, or halogen. Preferably, in D₁, and D₂, R₅, R₆, and R₇ areeach independently H, C₁˜C₁₂ alkyl, or C₁˜C₁₂ alkoxy. Most preferably,in D₁, and D₂, R₅, R₆, and R₇ are each independently H, or C₁˜C₁₂ alkyl.

In the above formula (I), B may be

wherein R₁₆, R₁₇, and R₁₈ are each independently H, C₁˜C₁₂ alkyl, C₁˜C₁₂alkoxy, or halogen, R₁₉, R₂₀, R₂₁, and R₂₂ are each independently H, orC₁˜C₁₂ alkyl, and Z is O, S, or Se.Preferably, B is

wherein R₁₆ is H, C₁˜C₁₂ alkyl, C₁˜C₁₂ alkoxy, or halogen, R₁₉, and R₂₂are each independently H, or C₁˜C₁₂ alkyl, and Z is O, S, or Se. Morepreferably, B is

wherein R₁₆ is H, C₁˜C₁₂ alkyl, C₁˜C₁₂ alkoxy, or halogen, R₁₉, and R₂₂are each independently H, or C₁˜C₁₂ alkyl, and Z is S. Most preferably,B is

wherein R₁₆, R₁₉, and R₂₂ are each independently H, or C₁˜C₁₂ alkyl, andZ is S.

In addition, according to one embodiment of the present invention, inthe above formula (I), B may be

wherein R₁₆ is H, C₁˜C₁₂ alkyl, C₁˜C₁₂ alkoxy, or halogen, R₁₉ is H, orC₁˜C₁₂ alkyl, and Z is O, S, or Se. Preferably, B is

wherein R₁₆ is H, C₁˜C₁₂ alkyl, C₁˜C₁₂ alkoxy, or halogen, R₁₉ is H, orC₁˜C₁₂ alkyl, and Z is S. More preferably, B is

wherein R₁₆ is H, C₁˜C₁₂ alkyl, or C₁˜C₁₂ alkoxy, R₁₉ is H, or C₁˜C₁₂alkyl, and Z is S. Still more preferably, B is

wherein R₁₆ and R₁₉ are each independently H, or C₁˜C₁₂ alkyl, and Z isS. Most preferably, B is

wherein R₁₆ and R₁₉ are H, and Z is S.

The specific examples of the dye compound represented by the aboveformula (I) are:

In the present invention, the molecule of the dye compound is presentedin form of free acid. However, the actual form of the dye compound ofthe present invention may be salt, and more likely, may be alkalinemetal salt or quaternary ammonium salt.

In addition, the aforementioned dye compound is used as a dye compoundfor a dye-sensitized solar cell.

Furthermore, the present invention also provides a dye-sensitized solarcell, which comprises the aforementioned dye compound. Thedye-sensitized solar cell of the present invention comprises: aphotoanode comprising the aforementioned dye compound; a cathode; and anelectrolyte layer disposed between the photoanode and the cathode.

In the dye-sensitized solar cell of the present invention, thephotoanode comprises: a transparent substrate, a transparent conductivelayer, a porous semiconductive layer, and a dye compound; wherein thedye compound is the aforementioned dye compound.

In the dye-sensitized solar cell of the present invention, the materialof the transparent substrate is not particularly limited, as long as thematerial of the substrate is a transparent material. Preferably, thematerial of the transparent substrate has good moisture resistance,solvent resistance and weather resistance. Thus, the dye-sensitizedsolar cell can resist moisture or gas from outsides by the transparentsubstrate. The specific examples of the transparent substrate include,but are not limited to, transparent inorganic substrates, such as quartzand glass; transparent plastic substrates, such as poly(ethyleneterephthalate) (PET), poly(ethylene 2,6-naphthalate) (PEN),polycarbonate (PC), polyethylene (PE), polypropylene (PP), and polyimide(PI). Additionally, the thickness of the transparent substrate is notparticularly limited, and can be modified according to the transmittanceand the demands for the properties of the dye-sensitized solar cell.Preferably, the material of the transparent substrate is glass.

Furthermore, in the dye-sensitized solar cell of the present invention,the material of the transparent conductive layer can be indium tin oxide(ITO), fluorine-doped tin oxide (FTO), ZnO—Ga₂O₃, ZnO—Al₂O₃, ortin-based oxides.

In addition, in the dye-sensitized solar cell of the present invention,the porous semiconductive layer is made of semiconductor particles.Suitable semiconductor particles may include Si, TiO₂, SnO₂, ZnO, WO₃,Nb₂O₅, TiSrO₃, and the combination thereof. Preferably, thesemiconductor particles are made from TiO₂. The average diameter of thesemiconductor particles may be 5 to 500 nm. Preferably, the averagediameter of the semiconductor particles is 10 to 50 nm. Furthermore, thethickness of the porous semiconductive layer is 5-25 μm.

Besides, the material of the cathode for the dye-sensitized solar cellis not particularly limited, and may include any material withconductivity. Otherwise, the material of the cathode can be aninsulating material, as long as there is a conductive layer formed onthe surface of the cathode, wherein the surface of the cathode is facedto the photoanode. The material of the cathode can be any material withelectrochemical stability. The unlimited examples suitable for thematerial of the cathode include Pt, Au, C, or the like.

Furthermore, the material used in the electrolyte layer of thedye-sensitized solar cell is not particularly limited, and can be anymaterial, which can transfer electrons and/or holes.

On the other hand, the present invention further provides a dyesolution, which comprises: (A) the aforementioned dye compound, whereinthe content of the dye compound is 0.01-1 wt %; and (B) an organicsolvent, wherein the content of the organic solvent is 99.99-99 wt %,and the organic solvent is selected from the group consisting ofacetonitrile, methanol, ethanol, propanol, butanol, dimethyl formamide,and N-methyl-2-pyrrolidinone.

Other objects, advantages, and novel features of the invention willbecome more apparent from the following detailed description when takenin conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The dye compound of the present invention can be synthesised by Schemes1 to 3.

As shown in Scheme 1, 7-bromo-9H-fluoren-2-ylamine is reacted with1-iodobutane to form (7-bromo-9H-fluoren-2-yl)-dibutyl amine (11). Then,(7-bromo-9H-fluoren-2-yl)-dibutyl amine (11) is reacted with5-formyl-2-thiopheneboronic acid by Suzuki coupling reaction to obtain5-(7-dibutylamino-9H-fluoren-2-yl)-thiophene-2-carbaldehyde (12a).Finally, in acetonitrile,5-(7-dibutylamino-9H-fluoren-2-yl)-thiophene-2-carbaldehyde (12a) isreacted with cyanoacetic acid by using piperidine as a catalyst, toobtain2-cyano-3-[5-(7-dibutylamino-9H-fluoren-2-yl)-thiophen-2-yl]-acrylicacid (13a).

As shown in Scheme 2, 7-bromo-9H-fluoren-2-ylamine is reacted with1-iodobutane to form (7-bromo-9,9-dibutyl-9H-fluoren-2-yl)-dibutylamine(21). Then, (7-bromo-9,9-dibutyl-9H-fluoren-2-yl)-dibutylamine (21) isreacted with 5-formyl-2-thiopheneboronic acid by Suzuki couplingreaction to obtain5-(9,9-Dibutyl-7-dibutylamino-9H-fluoren-2-yl)-thiophene-2-carbaldehyde(22a). Finally, in acetonitrile,5-(9,9-Dibutyl-7-dibutylamino-9H-fluoren-2-yl)-thiophene-2-carbaldehyde(22a) is reacted with cyanoacetic acid by using piperidine as acatalyst, to obtain2-Cyano-3-[5-(9,9-dibutyl-7-dibutylamino-9H-fluoren-2-yl)-thiophen-2-yl]-acrylicacid (23a).

As shown in Scheme 3, 7-bromo-9H-fluoren-2-ylamine is reacted with1-iodobutane to form 7-bromo-9,9-dibutyl-9H-fluoren-2-ylamine (31); and2-Iodo-9H-fluorene is reacted with 1-iodobutane to form9,9-dibutyl-2-iodo-9H-fluorene (32). Then,7-bromo-9,9-dibutyl-9H-fluoren-2-ylamine (31) is reacted with9,9-dibutyl-2-iodo-9H-fluorene (32) by Ullman coupling reaction toobtain(7-bromo-9,9-dibutyl-9H-fluoren-2-yl)-bis-(9,9-dibutyl-9H-fluoren-2-yl)amine(33). Next,(7-bromo-9,9-dibutyl-9H-fluoren-2-yl)-bis-(9,9-dibutyl-9H-fluoren-2-yl)amine(33) is reacted with 5-formyl-2-thiopheneboronic acid by Suzuki couplingreaction to obtain5-{7-[bis-(9,9-dibutyl-9H-fluoren-2-yl)amino]-9,9-dibutyl-9H-fluoren-2-yl}-thiophene-2-carbaldehyde(34a). Finally, in acetonitrile,5-{7-[bis-(9,9-dibutyl-9H-fluoren-2-yl)amino]-9,9-dibutyl-9H-fluoren-2-yl}-thiophene-2-carbaldehyde(34a) is reacted with cyanoacetic acid by using piperidine as acatalyst, to obtain3-(5-{7-[bis-(9,9-dibutyl-9H-fluoren-2-yl)amino]-9,9-dibutyl-9H-fluoren-2-yl}-thiophen-2-yl)-2-cyano-acrylicacid (35a).

The method for manufacturing the dye-sensitized solar cell of thepresent invention is not particularly limited, and the dye-sensitizedsolar cell of the present invention can be manufacture by the knownmethods in the art.

The material of the transparent substrate is not particularly limited,as long as the material of the substrate is a transparent material.Preferably, the material of the transparent substrate is a transparentmaterial with good moisture resistance, solvent resistance and weatherresistance. Thus, the dye-sensitized solar cell can resist moisture orgas from outsides by the transparent substrate. The specific examples ofthe transparent substrate include, but are not limited to, transparentinorganic substrates, such as quartz and glass; transparent plasticsubstrates, such as poly(ethylene terephthalate) (PET), poly(ethylene2,6-naphthalate) (PEN), polycarbonate (PC), polyethylene (PE),polypropylene (PP), and polyimide (PI). Additionally, the thickness ofthe transparent substrate is not particularly limited, and can bemodified according to the transmittance and the demands for theproperties of the dye-sensitized solar cell. In a specific embodiment,the material of the transparent substrate is a glass substrate.

Furthermore, the material of the transparent conductive layer can beindium tin oxide (ITO), fluorine-doped tin oxide (FTO), ZnO—Ga₂O₃,ZnO—Al₂O₃, or tin-based oxides. In a specific embodiment, fluorine-dopedtin oxide is used for the transparent conductive layer.

In addition, the porous semiconductive layer is made of semiconductorparticles. Suitable semiconductor particles may include Si, TiO₂, SnO₂,ZnO, WO₃, Nb₂O₅, TiSrO₃, and the combination thereof. First, thesemiconductor particles are prepared in a form of paste, and then thepaste is coated on the transparent conductive substrate. The coatingmethod used herein can be blade coating, spin coating, spry coating, orwetting coating. Additionally, the coating can be held for one time ormany times, in order to obtain a porous semiconductive layer withsuitable thickness. The semiconductive layer can be a single layer ormultiple layers, wherein each layer of the multiple layers is formed bysemiconductor particles with different diameters. For example, thesemiconductor particles with diameters of 5 to 50 nm is coated in athickness of 5 to 20 μm, and then the semiconductor particles withdiameters of 200 to 400 nm is coated in a thickness of 3 to 5 μmthereon. After drying the coated substrate under 50-100° C., the coatedsubstrate is sintered under 400-500° C. for 30 min to obtain amultilayer semicondictive layer.

The dye compound can be dissolved in a suitable solvent to prepare a dyesolution. Suitable solvents include, but are not limited to,acetonitrile, methanol, ethanol, propanol, butanol, dimethyl formamide,N-methyl-2-pyrrolidinone, and the combination thereof. Herein, thetransparent substrate coated with the semiconductive layer is dippedinto a dye solution to make the semiconductive layer absorb the dye inthe dye solution completely. After the dye absorption is completed, thetransparent substrate coated with the semiconductive layer is taken outand dried. Finally, a photoanode for a dye-sensitized solar cell isobtained.

Besides, the material of the cathode for the dye-sensitized solar cellis not particularly limited, and may include any material withconductivity. Otherwise, the material of the cathode can be aninsulating material, as long as there is a conductive layer formed onthe surface of the cathode, wherein the surface of the cathode is facedto the photoanode. The material of the cathode can be a material withelectrochemical stability. The unlimited examples suitable for thematerial of the cathode include Pt, Au, C, or the like.

Furthermore, the material used in the electrolyte layer of thedye-sensitized solar cell is not particularly limited, and can be anymaterial, which can transfer electrons and/or holes. In addition, theliquid electrolyte can be a solution of acetonitrile containing iodine,a solution of N-methyl-2-pyrrolidinone containing iodine, or a solutionof 3-methoxy propionitrile containing iodine. In a specific embodiment,the liquid electrolyte can be a solution of acetonitrile containingiodine.

One specific method for manufacturing the dye-sensitized solar cell ofthe present invention is presented as follow.

First, a paste containing TiO₂ particles with diameter of 20˜30 nm iscoated on a glass substrate covered with fluorine-doped tin oxide (FTO)for one time or several times. Then, the coated glass substrate issintered under 450° C. for 30 min.

The dye compound is dissolved in a mixture of acetonitrile and t-butanol(1:1 v/v) to formulate a dye solution. Then, the aforementioned glasssubstrate with porous TiO₂ layer is dipped into the dye solution. Afterthe porous TiO₂ layer absorbs the dye in the dye solution completely,the resulted glass substrate is taken out and dried. Finally, aphotoanode is obtained.

A glass substrate covered with fluorine-doped tin oxide is drilled toform an inlet with a diameter of 0.75 mm, wherein the inlet is used forinjecting the electrolyte. Then, a solution of H₂PtCl₆ is coated on theglass substrate covered with fluorine-doped tin oxide, and the glasssubstrate is heated to 400° C. for 15 min to obtain a cathode.

Sequentially, a thermoplastic polymer layer with a thickness of 60 isdisposed between the photoanode and the cathode. These two electrodesare pressed under 120 to 140° C. to adhere with each other.

Then, an electrolyte is injected, wherein the electrolyte is a solutionof acetonitrile containing 0.03 M I₂/0.3 M LiI/0.5 M t-butyl-pyridine.After the inlet is sealed with thermoplastic polymer layer, adye-sensitized solar cell of the present invention is obtained.

The following examples are intended for the purpose of illustration ofthe present invention. However, the scope of the present inventionshould be defined as the claims appended hereto, and the followingexamples should not be construed as in any way limiting the scope of thepresent invention. Herein, the molecule of the dye compound is presentedin form of free acid. However, the actual form of the dye compound ofthe present invention may be salt, and more likely, may be alkalinemetal salt or quaternary ammonium salt. Without specific explanations,the unit of the parts and percentages used in the examples is calculatedby weight, and the temperature is represented by Celsius degrees (° C.).The relation between the parts by weight and the parts by volume is justlike the relation between kilogram and liter.

Then, the method for preparing the dye compound of the present inventionwill be explained with referring to Schemes 1-3.

Example 1 Synthesis of (7-bromo-9H-fluoren-2-yl)-dibutylamine (11)

Under N₂ atmosphere, 0.52 parts of 7-bromo-9H-fluoren-2-ylamine, 1.47parts of 1-iodobutane, and 1.38 parts of potassium carbonate were addedinto 15 parts of dry dimethylformamide, followed by stirring and mixing.Then, the reaction mixture was heated to 120° C. and reacted for 24hours. After the reaction mixture was cooled, poured the water into thereaction mixture for quenching the reaction, and using the diethyl etherto extract the product, and magnesium sulfate was used for dehydration.After removing the solvent, the residual was purified with columnchromatography method by using dichloromethane/hexane co-solvent as aneluent, to obtain a compound (11) of the present example. This compoundwas in a form of a yellowish-brown solid, and the yield of this compoundwas 85%.

Example 2 Synthesis of5-(7-dibutylamino-9H-fluoren-2-yl)-thiophene-2-carbaldehyde (12a)

Under N₂ atmosphere, 0.37 parts of (7-bromo-9H-fluoren-2-yl)-dibutylamine (11), 0.19 parts of 5-formyl-2-thiopheneboronic acid, 0.41 partsof potassium carbonate, and 0.16 parts of PdCl₂(dppf) were added into 5parts of toluene and 5 parts of CH₃OH, followed by stirring and mixing.Then, the reaction mixture was heated to 60° C. and reacted for 18hours. After the reaction mixture was quenched by water, using thediethyl ether to extract the product, and magnesium sulfate was used fordehydration. After removing the solvent, the residual was purified withchromatography method column by using dichloromethane/hexane co-solventas an eluent, to obtain a compound (12a) of the present example. Thiscompound was in a form of a tangerine solid, and the yield of thiscompound was 61%.

Example 3 Synthesis of 4-(7-dibutylamino-9H-fluoren-2-yl)-benzaldehyde(12b)

The process for preparing the dye compound of the present example is thesame as that described in Example 2, except that5-formyl-2-thiopheneboronic acid is substituted with 0.18 parts of4-formylphenylboronic acid, to obtain a compound (12b) of the presentexample. This compound was in a form of yellow solid, and the yield ofthis compound was 53%.

Example 4 Synthesis of2-cyano-3-[5-(7-dibutylamino-9H-fluoren-2-yl)-thiophen-2-yl]-acrylicacid (13a)

Under N₂ atmosphere, 0.18 parts of5-(7-dibutylamino-9H-fluoren-2-yl)-thiophene-2-carbaldehyde (12a), 0.05parts of cyanoacetic acid, and 0.017 parts of piperidine were added intoacetonitrile, followed by stirring and mixing. Then, the reactionmixture was heated to 90° C. and reacted for 6 hours. After the reactionmixture was cooled to room temperature, the reaction mixture wasfiltrated to obtain a solid. Then, the solid was washed with water,ether, and acetonitrile sequentially to obtain a dark red solid.Finally, this crude was purified with column chromatography method byusing dichloromethane/methanol co-solvent as an eluent, to obtain acompound (13a) of the present example. This compound was in a form of adark red solid, and the yield of this compound was 73%.

Example 5 Synthesis of2-cyano-3-[4-(7-dibutylamino-9H-fluoren-2-yl)-phenyl]-acrylic acid (13b)

The process for preparing the dye compound of the present example is thesame as that described in Example 4, except that5-(7-dibutylamino-9H-fluoren-2-yl)-thiophene-2-carbaldehyde (12a) issubstituted with 0.18 parts of4-(7-dibutylamino-9H-fluoren-2-yl)-benzaldehyde (12b), to obtain acompound (13b) of the present example. This compound was in a form ofdark red solid, and the yield of this compound was 78%.

Example 6 Synthesis of(7-bromo-9,9-dibutyl-9H-fluoren-2-yl)-dibutylamine (21)

Under N₂ atmosphere, 0.52 parts of 7-bromo-9H-fluoren-2-ylamine, 2.21parts of 1-iodobutane, 0.67 parts of potassium tert-butoxide, and 0.83parts of potassium carbonate were added into 10 parts of drydimethylformamide and 10 parts of 1,4-dioxane, followed by stirring andmixing. Then, the reaction mixture was heated to 95° C. and reacted for24 hours. After the reaction mixture was cooled, poured the water intothe reaction mixture for quenching the reaction, using the diethyl etherto extract the product, and magnesium sulfate was used for dehydration.After removing the solvent, the residual was purified with columnchromatography method by using dichloromethane/hexane co-solvent as aneluent, to obtain a compound (21) of the present example. This compoundwas in a form of a light yellow solid, and the yield of this compoundwas 83%.

Example 7 Synthesis of5-(9,9-dibutyl-7-dibutylamino-9H-fluoren-2-yl)-thiophene-2-carbaldehyde(22a)

The process for preparing the dye compound of the present example is thesame as that described in Example 2, except that(7-bromo-9H-fluoren-2-yl)-dibutylamine (11) is substituted with 0.49parts of (7-bromo-9,9-dibutyl-9H-fluoren-2-yl)-dibutylamine (21), toobtain a compound (22a) of the present example. This compound was in aform of a tangerine solid, and the yield of this compound was 52%.

Example 8 Synthesis of4-(9,9-dibutyl-7-dibutylamino-9H-fluoren-2-yl)-benzaldehyde (22b)

The process for preparing the dye compound of the present example is thesame as that described in Example 7, except that5-formyl-2-thiopheneboronic acid is substituted with 0.18 parts of4-formylphenylboronic acid, to obtain a compound (22b) of the presentexample. This compound was in a form of a yellow solid, and the yield ofthis compound was 61%.

Example 9 Synthesis of2-cyano-3-[5-(9,9-dibutyl-7-dibutylamino-9H-fluoren-2-yl)-thiophen-2-yl]-acrylicacid (23a)

The process for preparing the dye compound of the present example is thesame as that described in Example 4, except that5-(7-dibutylamino-9H-fluoren-2-yl)-thiophene-2-carbaldehyde (12a) issubstituted with 0.23 parts of5-(9,9-dibutyl-7-dibutylamino-9H-fluoren-2-yl)-thiophene-2-carbaldehyde(22a), to obtain a compound (23a) of the present example. This compoundwas in a form of a red solid, and the yield of this compound was 86%.

Example 10 Synthesis of2-cyano-3-[4-(9,9-dibutyl-7-dibutylamino-9H-fluoren-2-yl)-phenyl]-acrylicacid (23b)

The process for preparing the dye compound of the present example is thesame as that described in Example 9, except that5-(9,9-dibutyl-7-dibutylamino-9H-fluoren-2-yl)-thiophene-2-carbaldehyde(22a) is substituted with 0.23 parts of4-(9,9-dibutyl-7-dibutylamino-9H-fluoren-2-yl)-benzaldehyde (22b), toobtain a compound (23b) of the present example. This compound was in aform of a tangerine solid, and the yield of this compound was 68%.

Example 11 Synthesis of 7-bromo-9,9-dibutyl-9H-fluoren-2-ylamine (31)

Under N₂ atmosphere, 0.52 parts of 7-bromo-9H-fluoren-2-ylamine, 2.21parts of 1-iodobutane, and 1.35 parts of potassium tert-butoxide wereadded into 20 parts of dry tetrahydrofuran, followed by stirring andmixing. Then, the reaction mixture was heated to 50° C. and reacted for18 hours. After the reaction mixture was cooled, water was used forquenching the reaction, diethyl ether was used for extracting theproduct, and magnesium sulfate was used for dehydration. After removingthe solvent, the residual was purified with column chromatography methodby using dichloromethane/hexane co-solvent as an eluent, to obtain acompound (31) of the present example. This compound was in a form of abrown-yellow solid, and the yield of this compound was 79%.

Example 12 Synthesis of 9,9-dibutyl-2-iodo-9H-fluorene (32)

Under N₂ atmosphere, 0.58 parts of 2-iodo-9H-fluorene, 1.10 parts of1-iodobutane, and 0.67 parts of potassium tert-butoxide were added into15 parts of dry tetrahydrofuran, followed by stirring and mixing. Then,the reaction mixture was heated to 50° C. and reacted for 12 hours.After the reaction mixture was cooled, poured the water into thereaction mixture for quenching the reaction, using the diethyl ether toextract the product, and magnesium sulfate was used for dehydration.After removing the solvent, the residual was purified with columnchromatography method by using hexane as an eluent, to obtain a compound(32) of the present example. This compound was in a form of a lightyellow solid, and the yield of this compound was 94%.

Example 13 Synthesis of(7-bromo-9,9-dibutyl-9H-fluoren-2-yl)-bis-(9,9-dibutyl-9H-fluoren-2-yl)amine(33)

Under N₂ atmosphere, 0.37 parts of7-bromo-9,9-dibutyl-9H-fluoren-2-ylamine (31), 0.89 parts of9,9-dibutyl-2-iodo-9H-fluorene (32), 0.17 parts of potassium hydroxide,0.11 parts of 1,10-phenanthroline, and 0.03 parts of cuprous chloridewere added into 10 parts of toluene, followed by stirring and mixing.Then, the reaction mixture was heated to 120° C. and reacted underreflux for 24 hours. After the reaction was quenched by water, diethylether was used for extracting the product, and magnesium sulfate wasused for dehydration. After removing the solvent, the residual waspurified with column chromatography method by usingdichloromethane/hexane co-solvent as an eluent, to obtain a compound(33) of the present example. This compound was in a form of a tangerinesolid, and the yield of this compound was 57%.

Example 14 Synthesis of5-{7-[bis-(9,9-dibutyl-9H-fluoren-2-yl)amino]-9,9-dibutyl-9H-fluoren-2-yl}-thiophene-2-carbaldehyde(34a)

The process for preparing the dye compound of the present example is thesame as that described in Example 2, except that(7-bromo-9H-fluoren-2-yl)-dibutylamine (11) is substituted with 0.92parts of(7-bromo-9,9-dibutyl-9H-fluoren-2-yl)-bis-(9,9-dibutyl-9H-fluoren-2-yl)amine (33), to obtain a compound (34a) of the present example. Thiscompound was in a form of a tangerine solid, and the yield of thiscompound was 38%.

Example 15 Synthesis of4-{7-[bis-(9,9-dibutyl-9H-fluoren-2-yl)-amino]-9,9-dibutyl-9H-fluoren-2-yl}-benzaldehyde(34b)

The process for preparing the dye compound of the present example is thesame as that described in Example 14, except that5-formyl-2-thiopheneboronic acid is substituted with 0.18 parts of4-formylphenylboronic acid, to obtain a compound (34b) of the presentexample. This compound was in a form of a yellow solid, and the yield ofthis compound was 48%.

Example 16 Synthesis of3-(5-{7-[Bis-(9,9-dibutyl-9H-fluoren-2-yl)amino]-9,9-dibutyl-9H-fluoren-2-yl}-thiophen-2-yl)-2-cyano-acrylicacid (35a)

The process for preparing the dye compound of the present example is thesame as that described in Example 4, except that5-(7-dibutylamino-9H-fluoren-2-yl)-thiophene-2-carbaldehyde (12a) issubstituted with 0.41 parts of 5-{7-[bis-(9,9-dibutyl-9H-fluoren-2-yl)amino]-9,9-dibutyl-9H-fluoren-2-yl}-thiophene-2-carbaldehyde (34a), toobtain a compound (35a) of the present example. This compound was in aform of a tangerine solid, and the yield of this compound was 51%.

Example 17 Synthesis of3-(4-{7-[Bis-(9,9-dibutyl-9H-fluoren-2-yl)amino]-9,9-dibutyl-9H-fluoren-2-yl}-phenyl)-2-cyano-acrylicacid (35b)

The process for preparing the dye compound of the present example is thesame as that described in Example 16, except that5-{7-[bis-(9,9-dibutyl-9H-fluoren-2-yl)amino]-9,9-dibutyl-9H-fluoren-2-yl}-thiophene-2-carbaldehyde (34a) is substituted with 0.42 parts of4-{7-[bis-(9,9-dibutyl-9H-fluoren-2-yl)-amino]-9,9-dibutyl-9H-fluoren-2-yl}-benzaldehyde (34b), to obtain a compound (35b) of the present example. Thiscompound was in a form of a tangerine solid, and the yield of thiscompound was 65%.

Example 18 Preparation of a Dye-Sensitized Solar Cell

A paste containing TiO₂ particles with diameter of 20˜30 nm was coatedon a glass substrate covered with fluorine-doped tin oxide (PTO) for onetime or several times, wherein the thickness of the glass substrate was4 mm and the electric resistance of the glass substrate is 10Ω/□. Then,the coated glass substrate was sintered under 450° C. for 30 min, andthe thickness of the sintered porous TiO₂ layer was 10 to 12 μm.

The dye compound prepared by Example 4 was dissolved in a mixture ofacetonitrile and t-butanol (1:1 v/v) to prepare a dye solutioncontaining 0.5 mM dye compound. Then, the aforementioned glass substratecovered with porous TiO₂ layer was dipped into the dye solution to makethe dye adhere on the porous TiO₂ layer. After 16 to 24 hours, theresulted glass substrate was taken out and dried, and then a photoanodewas obtained.

A glass substrate covered with fluorine-doped tin oxide was drilled toform an inlet with a diameter of 0.75 mm, wherein the inlet was used forinjecting the electrolyte. Then, a solution of H₂PtCl₆ (2 mg Pt in 1 mlethanol) was coated on the glass substrate covered with fluorine-dopedtin oxide, and the resulted glass substrate was heated to 400° C. for 15min to obtain a cathode.

Sequentially, a thermoplastic polymer layer with a thickness of 60 μmwas disposed between the photoanode and the cathode. These twoelectrodes were pressed under 120 to 140° C. to adhere with each other.

Then, an electrolyte was injected, wherein the electrolyte was asolution of acetonitrile containing 0.03 M I₂/0.3 M Lit/0.5 Mt-butyl-pyridine. After the inlet was sealed with thermoplastic polymerlayer, a dye-sensitized solar cell of the present example was obtained.

Example 19 Preparation of a Dye-Sensitized Solar Cell

The process for preparing the dye-sensitized solar cell of the presentexample is the same as that described in Example 18, except that the dyecompound prepared in Example 4 is substituted with the dye compoundprepared in Example 5.

Example 20 Preparation of a Dye-Sensitized Solar Cell

The process for preparing the dye-sensitized solar cell of the presentexample is the same as that described in Example 18, except that the dyecompound prepared in Example 4 is substituted with the dye compoundprepared in Example 9.

Example 21 Preparation of a Dye-Sensitized Solar Cell

The process for preparing the dye-sensitized solar cell of the presentexample is the same as that described in Example 18, except that the dyecompound prepared in Example 4 is substituted with the dye compoundprepared in Example 10.

Example 22 Preparation of a Dye-Sensitized Solar Cell

The process for preparing the dye-sensitized solar cell of the presentexample is the same as that described in Example 18, except that the dyecompound prepared in Example 4 is substituted with the dye compoundprepared in Example 16.

Example 23 Preparation of a Dye-Sensitized Solar Cell

The process for preparing the dye-sensitized solar cell of the presentexample is the same as that described in Example 18, except that the dyecompound prepared in Example 4 is substituted with the dye compoundprepared in Example 17.

Testing Methods and Results UV-Vis Spectrum

Dimethyl formamide was used as a solvent to prepare dye solutionscontaining 1.0×10⁻⁵M of the dye compounds prepared in Example 4, Example5, Example 9, Example 10, Example 16, and Example 17. Then, the UV-Visspectrum of each dye solution was measured.

Test for the Photoelectric Characteristics

The short circuit current (J_(SC)), open circuit voltage (V_(OC)),filling factor (FF), photoelectric conversion efficiency (η), andincident photon-to-current conversion efficiency (IPCE) of thedye-sensitized solar cells prepared by Examples 18-23 were measuredunder the illumination of AM 1.5 stimulated light. The testing resultsare shown in the following Table 1:

TABLE 1 Testing results of the dye and the dye-sensitized solar cellMolar absorption coefficient at the wavelength of the maximum absorption(M⁻¹cm⁻¹)/λ _(max) J_(SC) V_(OC) η Dye (nm) (mA/cm²) (V) FF (%) Example13a 25200/421 6.28 0.61 0.66 2.54 18 Example 13b 23200/384 8.40 0.600.63 3.15 19 Example 23a 66200/427 13.16 0.69 0.64 5.82 20 Example 23b73100/386 11.00 0.68 0.58 4.68 21 Example 35a 66800/421 10.28 0.69 0.654.90 22 Example 35b 35200/380 10.30 0.70 0.63 4.58 23

According to the results shown in Table 1, the dye compounds of thepresent invention have high molar absorption coefficient. Hence, thedye-sensitized solar cell using the dye compound of the presentinvention has good photoelectric conversion efficiency.

In conclusion, the present invention is different from the prior arts inseveral ways, such as in purposes, methods and efficiency, or even intechnology and research and design. Although the present invention hasbeen explained in relation to its preferred embodiment, it is to beunderstood that many other possible modifications and variations can bemade without departing from the scope of the invention as hereinafterclaimed. Hence, the scope of the present invention should be defined asthe claims appended hereto, and the foregoing examples should not beconstrued as in any way limiting the scope of the present invention.

What is claimed is:
 1. A dye compound represented by the followingformula (I), or a salt thereof:

wherein, R₁, R₂, R₃, and R₄ are each independently H, C₁˜C₁₂ alkyl,C₁˜C₁₂ alkoxy, or a halogen, and n is 1, 2, or 3; D₁, and D₂ are eachindependently C₁˜C₁₂ alkyl,

or D₁, D₂, and N bond together to form

wherein R₅, R₆, R₇, R₈, R₁₀, R₁₁, R₁₃, and R₁₄ are each independently H,C₁˜C₁₂ alkyl, C₁˜C₁₂ alkoxy, amino, or halogen, and R₉, R₁₂, and R₁₅ areeach independently H, or C₁˜C₁₂ alkyl; B is

wherein R₁₆ is H, C₁˜C₁₂ alkyl, C₁˜C₁₂ alkoxy, or halogen.
 2. The dyecompound as claimed in claim 1, wherein n is
 1. 3. The dye compound asclaimed in claim 1, wherein D₁, and D₂ are each independently C₁˜C₁₂alkyl,

wherein R₅, R₆, R₇, and R₈ are each independently H, C₁˜C₁₂ alkyl,C₁˜C₁₂ alkoxy, amino, or halogen, and R₉ is H, or C₁˜C₁₂ alkyl.
 4. Thedye compound as claimed in claim 1, wherein R₁, R₂, R₃, R₄, R₅, R₆, R₇,R₈, and R₁₆ are each independently H, C₁˜C₁₂ alkyl, or C₁˜C₁₂ alkoxy. 5.The dye compound as claimed in claim 4, wherein R₁, R₂, R₃, R₄, R₅, R₆,R₇, R₈, and R₁₆ are each independently H, or C₁˜C₁₂ alkyl.
 6. The dyecompound as claimed in claim 1, wherein D₁, and D₂ are eachindependently C₁˜C₁₂ alkyl, or

wherein R₅, R₆, and R₇ are each independently H, C₁˜C₁₂ alkyl, C₁˜C₁₂alkoxy, amino, or halogen.
 7. The dye compound as claimed in claim 6,wherein R₁, R₂, R₃, R₄, R₅, R₆, R₇, and R₁₆ are each independently H,C₁˜C₁₂ alkyl, C₁˜C₁₂ alkoxy.
 8. The dye compound as claimed in claim 7,wherein R₁, R₂, R₃, R₄, R₅, R₆, R₇, and R₁₆ are each independently H, orC₁˜C₁₂ alkyl.
 9. The dye compound as claimed in claim 8, wherein R₁₆ isH.
 10. The dye compound as claimed in claim 1, wherein the dye compoundis a dye compound for a dye-sensitized solar cell.
 11. A dye solution,comprising: (A) a dye compound represented by the following formula (I),or a salt thereof, wherein the content of the dye compound is 0.01-1 wt%:

wherein, R₁, R₂, R₃, and R₄ are each independently H, C₁˜C₁₂ alkyl,C₁˜C₁₂ alkoxy, or a halogen, and n is 1, 2, or 3; D₁, and D₂ are eachindependently C₁˜C₁₂ alkyl,

or D₁, D₂, and N bond together to form

wherein R₅, R₆, R₇, R₈, R₁₀, R₁₁, R₁₃, and R₁₄ are each independently H,C₁˜C₁₂ alkyl, C₁˜C₁₂ alkoxy, amino, or halogen, and R₉, R₁₂, and R₁₅ areeach independently H, or C₁˜C₁₂ alkyl; B is

wherein R₁₆ is H, C₁˜C₁₂ alkyl, C₁˜C₁₂ alkoxy, or halogen; and (B) anorganic solvent, wherein the content of the organic solvent is 99.99-99wt %, and the organic solvent is selected from the group consisting ofacetonitrile, methanol, ethanol, propanol, butanol, dimethyl formamide,and N-methyl-2-pyrrolidinone.
 12. The dye compound as claimed in claim1, wherein the formula (I) is the following formula (13b), (23b), or(35b):